Technical Field
The present invention relates to a communication technique, and particularly, to a mobile communication system in which a mobile station apparatus measures reception quality of a signal received from a base station apparatus to transmit reception quality information to the base station apparatuses, and relates to a base station apparatus and a mobile station apparatus which are adapted to the mobile communication system.
Background Art
Recently, demand for data communication is increasing in a mobile communication system, and various techniques are proposed to obtain high frequency use efficiency meeting the increase in the communication data associated with the demand. One of the techniques for increasing the frequency use efficiency is OFDMA (Orthogonal Frequency Division Multiple Access). The OFDMA relates to a technique of modulation method of communication in which the same frequency is used in all cells in a communication area constituted by the cells, and the OFDMA can achieve fast data communication. In the scheduling of transmission packets in the OFDMA system, a method is known in which mobile station apparatuses transmit CQI (Channel Quality Indicator), which is information indicating the reception quality of a downlink state for sub-carriers in wideband, to a base station apparatus, and the base station apparatus performs scheduling of the packets based on the CQI of sub-carriers in wideband transmitted from the mobile station apparatuses.
Furthermore, in the scheduling of transmission packets in an OFDM (Orthogonal Frequency Division Multiplexing) system using a plurality of sub-carriers, a technique is also known in which mobile station apparatuses evaluate each channel states of a downlink (frequency characteristics, or characteristics such as transmission loss dependent on the frequency) and transmit information with quantized each channel states to a base station apparatus, and the base station apparatus determines sub-carriers to be assigned to the mobile station apparatuses based on the transmitted information (see, Patent Document 1 below). FIG. 5 is a diagram showing an overview of a conventional communication method between a base station apparatus and a mobile station apparatus. FIG. 5(A) is a diagram showing a system configuration example, and FIG. 5(B) is a diagram showing a characteristic example. Having received downlink information 205 of a downlink line used for reception quality measurement from a base station apparatus 201, a mobile station apparatus measures the reception quality of each channel (FIG. 5(B)) based on the downlink information and quantizes the measured reception quality of each channel to create a channel profile of a propagation path.
The channel profile created by the mobile station apparatus 203 is transmitted, from the mobile station apparatus 203 to the base station apparatus 201, as reception quality information 207 using an uplink line. The base station apparatus 201 executes processing, such as adaptive modulation and coding or frequency selective scheduling, upon signals transmitted from the base station apparatus 201 to the mobile station apparatus 203 based on the reception quality information 207.
In relation to the transmission of reception quality information by the mobile station apparatus to the base station apparatus, transmission from the mobile station apparatus to the base station apparatus by using a dedicated uplink control channel (hereinafter, referred to as PUCCH (Physical Uplink Control Channel)) and an uplink shared data channel (hereinafter, PUSCH (Physical Uplink Shared Channel)) is examined in the evolution of third generation wireless access (Evolved Universal Terrestrial Radio Access) examined in 3GPP (3rd Generation Partnership Project) that is an international standardization project. For example, Non-Patent Document 1 described below proposes transmitting the reception quality information using the PUCCH or the PUSCH depending on the type of services, in which required reception quality information varies, when the mobile station apparatus transmits the reception quality information to the base station apparatus.
Patent Document 1: JP Patent Publication (Kokai) No. 2005-130491A
Non-Patent Document 1: “CQI handling during DRX”, 3GPP, TSG RAN WG2 Meeting #58, R2-071901, May 2007